Topical treatment in pain medicine: from ancient remedies to modern usage

Topical menthol for chemotherapy-induced peripheral neuropathy: a randomised controlled trial in breast cancer

OBJECTIVES

Chemotherapy-induced peripheral neuropathy (CIPN) symptom is one of the side effects of paclitaxel in breast cancer patients. This randomised controlled study was conducted to investigate the effect of topical menthol applied on the hands and feet of breast cancer patients receiving chemotherapy on CIPN symptoms.

METHODS

60 breast cancer patients receiving chemotherapy were randomly assigned to an intervention group (n=30), which received topical menthol treatment, or a control group (n=30), which received standard care. Both groups continued their routine pharmacological treatments throughout the study. The intervention group applied 1% menthol topically to their hands and feet two times a day. The effect of the intervention on CIPN symptoms was evaluated 3 weeks and 6 weeks after the intervention.

RESULTS

The intervention group showed a significantly greater improvement in CIPN symptoms over time compared with the control group, with an effect size of η2=0.214 for the group×time interaction. Additionally, the intervention group exhibited a notable positive change in the exposure subscale of the CIPN rating scale, with an effect size of η2=0.114.

CONCLUSIONS

Topical application of menthol significantly mitigates the symptoms of CIPN in breast cancer patients. This study supports the use of menthol as an effective adjunctive treatment for CIPN.

TRIAL REGISTRATION NUMBER

NCT05429814.

Topically Applied Therapies for the Treatment of Skin Disease: Past, Present, and Future

The purpose of this review is to summarize essential biological, pharmaceutical, and clinical aspects in the field of topically applied medicines that may help scientists when trying to develop new topical medicines. After a brief history of topical drug delivery, a review of the structure and function of the skin and routes of drug absorption and their limitations is provided. The most prevalent diseases and current topical treatment approaches are then detailed, the organization of which reflects the key disease categories of autoimmune and inflammatory diseases, microbial infections, skin cancers, and genetic skin diseases. The complexity of topical product development through to large-scale manufacturing along with recommended risk mitigation approaches are then highlighted. As such topical treatments are applied externally, patient preferences along with the challenges they invoke are then described, and finally the future of this field of drug delivery is discussed, with an emphasis on areas that are more likely to yield significant improvements over the topical medicines in current use or would expand the range of medicines and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of the skin and its associated diseases and current treatments along with the intricacies of topical formulation development should be helpful in making judicious decisions about the development of new or improved topical medicines. These aspects include the choices of the active ingredients, formulations, the target patient population's preferences, limitations, and the future with regard to new skin diseases and topical medicine approaches.

Menthol: An underestimated anticancer agent

Menthol, a widely used natural, active compound, has recently been shown to have anticancer activity. Moreover, it has been found to have a promising future in the treatment of various solid tumors. Therefore, using literature from PubMed, EMBASE, Web of Science, Ovid, ScienceDirect, and China National Knowledge Infrastructure databases, the present study reviewed the anticancer activity of menthol and the underlying mechanism. Menthol has a good safety profile and exerts its anticancer activity via multiple pathways and targets. As a result, it has gained popularity for significantly inhibiting different types of cancer cells by various mechanisms such as induction of apoptosis, cell cycle arrest, disruption of tubulin polymerization, and inhibition of tumor angiogenesis. Owing to the excellent anticancer activity menthol has demonstrated, further research is warranted for developing it as a novel anticancer agent. However, there are limitations and gaps in the current research on menthol, and its antitumor mechanism has not been completely elucidated. It is expected that more basic experimental and clinical studies focusing on menthol and its derivatives will eventually help in its clinical application as a novel anticancer agent.

The effects of Biofreeze and superficial heat on masticatory myofascial pain syndrome

Purpose:

This study aims to assess the influence of superficial heat and Biofreeze on pain, mouth opening (mm), and quality of life in patients with masticatory myofascial pain syndrome (MPS).

Materials and methods:

52 patients with MPS were included in the study. They were randomly divided into two groups. Patients in the Biofreeze group (n = 26) applied 3.5% menthol gel to the masseter and temporal muscles twice a day for seven days, while the other group applied superficial heat. Baseline, 7th, and 21st days of VAS, mouth opening (mm), and Oral Health Impact Profile-14 (OHIP-14) scores of the patients were evaluated statistically.

Results:

The mouth opening increased by 4.27 ± 3.80 mm in the Biofreeze group and 2.58 ± 2.16 mm in the superficial heat group. In each group, a significant decrease in VAS and OHIP-14 scores was observed on the 7th day compared to the baseline values (p<0.001). There was no statistically significant difference between the two applications on myofascial pain, mouth opening (mm), and OHIP-14 total score variables. The favorable effects of both applications on these parameters were limited to the duration of use.

Conclusion:

Biofreeze and superficial heat in MPS were found to increase the quality of life, but the limited effectiveness of these applications underlines the importance of the underlying factors.

Physicochemical Analysis of Medicated Ointment Enriched with Ginger (Zingiber officinale) Oil

Zingiber officinale rhizome has been revered as a culinary and medicinal spice in many traditional cultures. The essential oil from this plant has been proven to cure diseases of fighting infections by decreasing cholesterol and enhancing weight loss. Therefore, the benefits of this plant must be fully utilised either using raw or ginger based-products. Thus, this study aims to formulate herbal ointments with different concentration of ginger oil as well as to investigate the effect of varying concentration of oil on the ointment properties. In this work, five different ointment formulations were evaluated with various ratios of ginger to virgin coconut oil. All formulated semi-solid ointments were tested for physicochemical properties including hardness, viscosity, pH and turbidity. In this study, the properties of the developed ointment were compared with the commercial product as a benchmark. The developed ointment showed a good result of pH values where all ointments are ranging from 6.03 to 6.19. The ratio of 5:95 of ginger to virgin coconut oil was the best formulation where the tested properties were almost similar to the commercial ointment. Accordingly, the developed ointment in this study can be considered as suitable to be used to the external human body such as chest and nose to heal and protect the respiratory problems.

Fenugreek dermal patch, a new natural topical antinociceptive medication for relieving the postherniotomy pain, a double-blind placebo controlled trial

Background

Fenugreek seeds have shown antinociceptive effect in animal studies. This double-blind placebo controlled trial was designed to study the effect of fenugreek transdermal patch 10% (FDP) for management of inguinal hernia (IH) post-operative pain.

Methods

Standardized extract of fenugreek seeds was used for FDP formulation. Ninety patients treated with 10% FDP, diclofenac dermal patch 1% (DP) and placebo twice daily after IH surgery. The pain intensity score was evaluated using a visual analogue score (VAS) up to 48 h after operation. Morphine consumption and diclofenac suppository demand were evaluated too.

Results

The pain score was significantly reduced in FDP group in comparison with the placebo group. This effect was also significantly different from DP up to 6 h after surgery (p<0.05). Morphine consumption and diclofenc suppository demand were significantly decreased in FDP group (p<0.05).

Conclusion

In all, results of the present study indicated that FDP decreases pain score and demand for morphine in post-surgery patients in comparison to diclofenac patch, and this preparation could be a suit option as a natural antinociceptive agent for pain management.

The HECT ubiquitin E3 ligase Smurf2 degrades μ-opioid receptor 1 in the ubiquitin-proteasome system in lung epithelial cells

Opioids are widely used for relieving clinical acute or chronic pain. The biological effects of opioids are through activating μ-opioid receptor 1 (MOR1). Most studies have focused on the consequences of agonist-induced MOR1 phosphorylation, ubiquitination, and internalization. Agonist-mediated MOR1 degradation, which is crucial for receptor stability and responsiveness, has not been well studied. E3 ubiquitin-protein ligase SMURF2 (Smurf2), a homolog to E6AP carboxy terminus (HECT) ubiquitin E3 ligase, has been shown to regulate MOR1 ubiquitination and internalization; however, its role in MOR1 degradation has not been studied. Here, we demonstrate that Smurf2 mediates [d-Ala²,N-MePhe⁴,Gly⁵-ol]-enkephalin (DAMGO, an agonist of MOR1)-induced MOR1 ubiquitination and degradation. DAMGO decreased MOR1 levels in the ubiquitin-proteasome system. MOR1 was modified by a Lys48-linked polyubiquitin chain. Overexpression of Smurf2 induced MOR1 ubiquitination and accelerated DAMGO-induced MOR1 degradation, whereas downregulation of Smurf2 attenuated MOR1 degradation. Furthermore, DAMGO increased lung epithelial cell migration and proliferation, and the effect was attenuated by overexpressing Smurf2. Collectively, these data unveil that Smurf2 negatively regulates MOR1 activity by reducing its stability. We also demonstrate an unrevealed biological function of MOR1 in lung epithelial cells. DAMGO-MOR1 promote cell migration and proliferation in lung epithelial cells, suggesting a potential effect of DAMGO in lung repair and remodeling after lung injury.

Pharmacies for pain and trauma in ancient Greece

PURPOSE

To summarize pharmacies for pain and trauma in ancient Greece, to present several pharmaceutical/therapeutical methods reported in myths and ancient texts, and to theorize on the medical explanation upon which these pharmacies were used.

METHOD

A thorough literature search was undertaken in PubMed and Google Scholar as well as in physical books in libraries to summarize the pharmacies and pain practices used for trauma in ancient Greece.

RESULTS

Archeological findings and historical texts have revealed that humans have always suffered from diseases and trauma that were initially managed and healed by priests and magicians. In early Greek antiquity, the term pharmacy was related to herbal inquiries, with the occupants called charmers and pharmacists. Additionally, apart from therapeutic methods, ancient Greeks acknowledged the importance of pain therapy and had invented certain remedies for both acute and chronic pain management. With observations and obtaining experience, they used plants, herbs, metals and soil as a therapeutic method, regardless of the cultural level of the population. They achieved sedation and central and peripheral analgesia with opium and cold, as well as relaxation of smooth muscle fibers and limiting secretions with atropina.

CONCLUSION

History showed a lot of experience obtained from empirical testing of pain treatment in ancient people. Experience and reasoning constructed an explanatory account of diseases, therapies and health and have provided for the epistemology of medicine.

The role and mechanism of action of menthol in topical analgesic products

WHAT IS KNOWN AND OBJECTIVE

Menthol has been used as a non-opioid pain reliever since ancient times. A modern understanding of its molecular mechanism of action could form the basis for generating targets for discovery of novel non-opioid analgesic drugs.

METHODS

The PubMed database was queried using search words related to menthol, pain and analgesia. The results were limited to relevant preclinical studies and clinical trials and reviews published in English during the past 5 years, which yielded 31 reports. The bibliographies of these articles were sources of additional supporting articles.

RESULTS

Menthol is a selective activator of transient receptor potential melastatin-8 (TRPM8) channels and is also a vasoactive compound. As a topical agent, it acts as a counter-irritant by imparting a cooling effect and by initially stimulating nociceptors and then desensitizing them. Topically applied menthol may also activate central analgesic pathways. At high concentrations, menthol may generate cold allodynia.

WHAT IS NEW AND CONCLUSIONS

Recent elucidation of TRPM8 channels has provided a molecular basis for understanding the molecular action of menthol and its ability to produce both a cooling sensation and reduction in pain associated with a wide variety of pain(ful) conditions. The more modern mechanistic understanding of menthol and its pharmacologic mechanism of action may lead to an expanded role for this substance in the search for replacements for opioid analgesics, particularly those that can be applied topically.

Deformable Nanovesicles Synthesized through an Adaptable Microfluidic Platform for Enhanced Localized Transdermal Drug Delivery

Phospholipid-based deformable nanovesicles (DNVs) that have flexibility in shape offer an adaptable and facile method to encapsulate diverse classes of therapeutics and facilitate localized transdermal delivery while minimizing systemic exposure. Here we report the use of a microfluidic reactor for the synthesis of DNVs and show that alteration of input parameters such as flow speeds as well as molar and flow rate ratios increases entrapment efficiency of drugs and allows fine-tuning of DNV size, elasticity, and surface charge. To determine the ability of DNV-encapsulated drug to be delivered transdermally to a local site, we synthesized, characterized, and tested DNVs carrying the fluorescently labeled hydrophilic bisphosphonate drug AF-647 zoledronate (AF647-Zol). AF647-Zol DNVs were lyophilized, resuspended, and applied topically as a paste to the calvarial skin of mice. High-resolution fluorescent imaging and confocal microscopy revealed significant increase of encapsulated payload delivery to the target tissue-cranial bone-by DNVs as compared to nondeformable nanovesicles (NVs) or aqueous drug solutions. Interestingly, NV delivery was not superior to aqueous drug solution. Our studies show that microfluidic reactor-synthesized DNVs can be produced in good yield, with high encapsulation efficiency, reproducibility, and stability after storage, and represent a useful vehicle for localized transdermal drug delivery.

Health-promoting properties of compounds derived from Capsicum sp. A review

This article presents multidirectional effects of capsaicin and its natural derivatives as well as natural and synthetic analogs in term of their therapeutic properties. Active agents present in various Capsicum genus plants exert analgesic, anti-inflammatory, antibacterial, antioxidant and gastroprotective effects. Furthermore, capsaicin positively influences the metabolism of lipids. Numerous research show that capsaicinoids inhibit proliferation and migration process of cancer cells, what makes them molecules of high interest in oncology. Among broad range of positive activities, we have focused only on those properties that have already found application in medicine or seemed to be the most probably used in the near future. Even if in low or single doses this compound has been reported successful in numerous therapies, the negative consequences of high doses or prolonged administration is also discussed in the review.